Building energy conservation and photovoltaic power generation are important development trends of modern construction industry. Accordingly, a building integrating photovoltaic is a new technique of great potential and significant value. A photovoltaic device for the roof of a building mainly comprises battery assemblies constructed by solar cells and carriers, and the battery assemblies are mounted on the part of the roof facing the sun. In the solar battery assemblies, light energy is converted into electrical energy which is gathered and input to an electrical grid. There are numbers of relatively mature technical solutions for gathering and inputting electrical energy to an electrical grid. The photovoltaic device generally has a structure, as shown in FIG. 1, comprising: pillars 31, beams 32 with dividing strip 34 and grilles 35 mounted thereon, and a ceiling 33; a house panel 36 is mounted on the grilles 35, a waterproof layer (or a felt layer) 37 is disposed on the house panel 36, tiles are covered on the waterproof layer 37, and battery assemblies 38 are mounted on the tiles. The above technique for the photovoltaic roof has disadvantages of: (1) complex structure, inconvenient mounting, great labor needs and difficulties in working on the roof; (2) large materials consumption, a large number of steps of materials processing and high labor costs; (3) non-durability, vulnerability, short life; (4) poor strength of connection between the roof and the battery assemblies and inconvenient maintenance and replacement; and (5) unfashionable and cumbersome appearance. In addition, connections and junctions in the existing roof are filled and sealed with bricks, cement, felt, glue, or the like, thus resulting in inconvenience in construction, poor performance in leakage and immersion prevention, and difficulties in maintenance.
Additionally, since the ordinary photovoltaic device mounted with battery assemblies is required to resist wind load for fifty year return period, a cement base is needed to be pre-constructed, which will damage the original roof; the repairing of the cement base and the roof waterproof layer will increase the cost of the photovoltaic system; in addition, errors occurring in both processing and fitting an existing holder will result in difficulties in mounting the holder. Moreover, the ordinary photovoltaic device has a great balance weight, thus requiring strong support for the roof.